I've installed my GX on my comp, updated the drivers, the Studio Farm software, etc. The LED switched to green. I plugged my guitar onto it, and there's absolutely no sound, even if I plug earphones to the GX's jack.
I've tried to set the default devices for playback and recording back and forth, nothing.
When I select the GX as default, there's no sound coming from my comp's speakers, but neither from the GX.

Any ideas what should I do?
The volume is already up on everything. Btw I'm using Win 7 64-bit and a Yamaha amp + 2 Wharfedale 125W speakers. Still no sound. Not even noise or anything. I'm starting to get mad.